Did you overload the transformers? How many watts are they rated for and how much load did you place on them? Never exceed 80% of the transformer capacity in bulb wattage or you could be asking for trouble. Remember, you also lose "wattage" in wire resistance, so if you are maxing out the transformers you are probably way over capacity which would cause a thermal overload and in turn make the internal fuse or breaker to trip.

Did you overload the transformers? How many watts are they rated for and how much load did you place on them? Never exceed 80% of the transformer capacity in bulb wattage or you could be asking for trouble. Remember, you also lose "wattage" in wire resistance, so if you are maxing out the transformers you are probably way over capacity which would cause a thermal overload and in turn make the internal fuse or breaker to trip.

I replaced a 600 watt transformer. 2 lines-3- 50watt bulbs on each line not over loaded. Does a bad bulb ever cause a dead short.

Highly unlikely there could be a dead short in an incandescent bulb - filaments are so thin, they just melt and break causing an open circuit. Socket's, however, can short out, single contact bayonet types are especially vulnerable. The short may only occur when a lamp is inserted.

Has your client recently added anything new to that circuit inside the home that could be bumping up your total amperage and causing the breaker to trip? (did you say the transformers pop or the circuit breaker pops? Wasn't sure which). Did you do any rewiring and perhaps cross wires from one trans to another?Posted via Mobile Device